1. Field of the Invention
The present invention pertains to a fertilizer spreader using compressed air as the spreading medium, and more particularly, pertains to a compressed air fertilizer spreader on a truck chassis having midship mounted booms where the booms pivot towards the rear of the truck chassis. The air fertilizer spreader also uses dual particle accelerators for propelling of the fertilizer from metering assemblies to boom tubes.
2. Description of the Prior Art
Prior art fertilizer spreaders have usually had boom assemblies which mount on the rear of a truck chassis which extend outwardly from either side of the rear when in operation and pivot forwardly towards the front of the vehicle during storage and transportation. The prior art fertilizer spreaders provided a very rear end-heavy structure which was awkward, since it swung toward an interfering object or structure when the truck was steered away from the interfering object.
Additionally, and more importantly, the boom structure is subjected to far less damaging vertical forces which occur as this off road vehicle traverses rough ground, since it is mounted midway between the front and rear axles rather than cantilevered behind the rear axle.
Another prior art problem was achieving even spreading of fertilizer from the fertilizer box out through boom tubes. The prior art generally used forced air to propel fertilizer down boom tubes to the end of the tube. Forced air principles do not always provide for even regulation and distribution of the fertilizer from a metering or dispensing point to the end of the boom tube, resulting in uneven application of the fertilizer. Further, prior art forced air spreaders would cause severe abrasion in the boom tubes at the tube bend points, whereas the secondary particle accelerator considerably ameliorates this problem.
One particular prior art reference is U.S. Pat. No. 3,568,937, issued Mar. 9, 1971, to Gratalop. This patent is for a forced air spreader for spreading pulverulent or granular material and includes provisions for distributed material passing transversely into the neck of a venturi which, at its inlet, receives air supplied by a centrifugal fan which produces, in the respective pipe connection, a suction effect that draws in the said material. The material is then entrained by the current of air, being projected out of the venturi with acceleration and escaping through the respective pivotally mounted tube, which, at its end, is provided with a deflector dividing element for dispersing material thus entrained and projected where the pivotally mounted tubes effect the uniform distribution of the material over the ground. The prior art reference references a series of venturi and a pipe connection leading from each proportioning unit into the neck of the venturi. The prior art patent states that "there is a suction effect that draws in the said material, this material being entrained by the current of air, being projected out a venturi with acceleration, and escaping through the respective pivotal mounted tube, which at its end is provided with a deflector or dividing element disbursing the material thus entrained and projected." The description of the prior art reference is substantially verbatim from selected portions of the specification and claims.
The present invention pertains to a air fertilizer spreader which uses a dual particle accelerator principle for propelling fertilizer with a first particle accelerator from a metering assembly to boom tubes, and a second particle accelerator to propel fertilizer down the boom tubes. Additionally, the secondary particle accelerator will reduce wear at toe bend points in the distribution tubes. The boom tubes are also pivotally mounted providing a substantially air tight seal with the remaining tubes providing for integrity of the system. The boom tubes are pivotally mounted in a substantially vertical plane for mating with secondary particle accelerator outlets.